Currently, doors are typically framed with a jamb that surrounds the door. The jamb acts as a stop to fix the door in the closed position and seals the door opening against air penetration and weather. Most exterior doorways and some interior doorways have a threshold plate installed on the floor. The threshold plate is usually constructed of a rigid, nonporous wear and corrosion resistant material. When used with a sealing device typically extending beyond the bottom of a door, the threshold also serves to block air infiltration and weather at the interface between the door and the threshold. The threshold can also act to seal the door opening against fire. Conventionally, the threshold is attached to the floor or other support surface below the threshold with adhesives and/or screws. The threshold is sometimes sealed to the floor or support surface using a caulk.
Some buildings are constructed as modular building units. These buildings are normally constructed at a factory on a chassis with wheels. When the building is completed, it is then towed to its final location. Manufacturing efficiency methods are employed to speed the assembly of these modular buildings. One such manufacturing efficiency method includes the installation of modular doors to reduce the installation time attributable to installing a door to the doorway of a modular building.
A modular door is typically supplied as a complete door, jamb, and threshold assembly. Modular doors produced by Elixir Industries (24800 Chrisanta Drive, Suite 210, Mission Viejo, Calif. 92691) can be viewed on the Internet. Similarly, modular doors produced by Pocahontas Aluminium Company Inc. (physical address unknown) can be also viewed on the Internet. Further, modular doors are produced or distributed by Active Door & Window Co. (644 Union Ave., Holtsville, N.Y. 11742). Finally, modular doors produced by Philips Products (3221 Magnum Drive, Elkhart, Ind. 46516) may be viewed on the Internet.
To install the modular door assembly, the modular door assembly is placed into a prepared opening in a wall of the building and fastened to the wall by screws and/or other means. A problem with current modular door assemblies is that when the modular door is mounted in the door opening, a flat threshold allows water, air, and insect infiltration to the floor or support beneath the threshold if all the openings are not caulked or if applied caulk cracks or deteriorates. In particular, where a threshold is secured to the floor or support surface by inserting fasteners through holes in a top surface of the threshold, the hole generally presents a passageway for water, dirt, and other particulate matter to contact the floor or support surface, thereby causing rot and/or other deterioration. Over time, and especially if water has been allowed to contact the support beneath the threshold, the wall opening below the threshold often deteriorates significantly. In a case where this wear and/or rot has taken place, the overall doorway stability is compromised as well as rendering subsequent replacement of a door troublesome since the deteriorated door opening will be harder to seal and is cosmetically unappealing. Ultimately, deterioration of the door opening must sometimes be solved by rework of the building structure itself, which can be a time consuming and costly endeavor. To prevent infiltration of water, insects, and air, the application of caulk or the use of a door with four side flanges is often employed. In order to improve the appearance of doors, custom cut molding may be applied to cover unsightly edges of the doorway. However, these installation methods are costly and time consuming.
Modular doors are typically constructed with a threshold mounting flange. This mounting flange forms part of the door jamb. It is generally formed as a flat surface parallel to the face of the door that will allow the modular door assembly to be screwed directly to the face of a wall. As mentioned above, some modular door assemblies also have a mounting flange around all four sides of the door. The threshold mounting flange extends beneath the threshold approximately perpendicular to the underside of the threshold and is generally in plane with the top and side mounting flanges. In such cases, the mounting flange forms an integral and irremovable part of the threshold. Modular door assemblies with four side mounting flanges give additional support to the threshold and improve sealing between the threshold and the wall, but these assemblies are easily damaged and difficult to handle prior to installation. In storage, the modular door assemblies are often situated to rest on one of the mounting flanges, which causes damage (sometimes irreparable) to the mounting flange and renders the entire assembly useless or significantly reduces ease of installation and/or effectiveness during its service life. In addition, during the installation process, the modular door assembly is often transported by sliding the assembly along a floor in a manner that the thin edges of the mounting flanges dig into the floor, causing damage to the door assembly, the floor, and increasing the difficulty of maneuver the door assembly. These problems are worsened when the four side-mounting flanges are constructed of weak or lightweight materials that are more easily damaged by improper handling and lead to a shortened service life.